Social factors releasing and controlling aggression are under study in group of mangabeys, stumptail, pigtail and Celebes macaques. In addition, through collaboration with NIMH grant 20483, multiple groups of rhesus monkeys are also being investigated. Familianty, past social histories, and species membership are examined as factors influencing the release of aggression by selective introduction of one or more individuals into a group. Age and sex parameters are similarly explored. The control of aggression is being studied by monitoring wounding, patterns of agonistic expression and interference in aggressive episodes. Kinship, partner preference, age and sex all significantly influence such patterns and are being quantitatively assessed. This study will also assess the importance of factors in the social organization itself, such as the socionomic sex ratio, as they influence aggressive frequencies. Males will be studied in all male groups and when with the same heterosexual group with different adult male densities in order to see how such factors influence agonistic frequencies in each individual male. In addition the measures of the influence of female cycles on sexual behavior and agonistic frequencies will be used to test theories of male and female competition and hormonal contributions to aggression.